Method for making an epoxide

ABSTRACT

Process for preparing an epoxide, wherein halogenated ketones are formed as by-products and there is at least one treatment intended to remove at least part of the halogenated ketones formed.

The present patent application is a 371 of PCT/EP2006/062437 filed May19, 2006. In addition, this application claims the benefit of patentapplication FR 05.05120 and of patent application EP 05104321.4, bothfiled on 20 May 2005, and of provisional U.S. patent applications60/734,659, 60/734,627, 60/734,657, 60/734,658, 60/734,635, 60/734,634,60/734,637 and 60/734,636, all filed on 8 Nov. 2005, the content ofwhich is incorporated here by reference.

The present invention relates to a process for preparing an epoxide.Epoxides are important raw materials for the production of othercompounds.

Ethylene oxide is used, for example, for the production of ethyleneglycol, of di- and polyethylene glycols, of mono-, di- andtriethanolamines, etc. (see K. Weissermel and H.-J. Arpe in IndustrialOrganic Chemistry, Third, Completely Revised Edition, VCH, 1997, page149). Propylene oxide is an important intermediate in the preparation ofpropylene 1,2-glycol, of dipropylene glycol, of ethers of propyleneglycol, of isopropylamines, etc. (see K. Weissermel and H.-J. Arpe inIndustrial Organic Chemistry, Third, Completely Revised Edition, VCH,1997, page 275). Epichlorohydrin is an important raw material for theproduction of glycerol, of epoxy resins, of synthetic elastomers, ofglycidyl ethers, of polyamide resins, etc. (see Ullmann's Encyclopediaof Industrial Chemistry, Fifth Edition, Vol. A9, p. 539).

In the industrial production of propylene oxide the most commonly usedtechnology comprises the following steps: hypochloration of propylene tomonochloropropanol and dehydrochloration of the monochloropropanol topropylene oxide by means of an aqueous alkaline solution.

In the industrial production of epichlorohydrin the most commonly usedtechnology comprises the following steps: high-temperature free-radicalsubstituted chlorination of propylene or allyl chloride,hypochlorination of the allyl chloride thus synthesized todichloropropanol, and dehydrochlorination of the dichloropropanol toepichlorohydrin by means of an aqueous alkaline solution. Anothertechnology, used on a smaller scale, comprises the following steps:catalytic acetoxylation of propylene to allyl acetate, hydrolysis of theallyl acetate to allyl alcohol, catalytic chlorination of the allylalcohol to dichloropropanol, and alkaline dehydrochlorination of thedichloropropanol to epichlorohydrin. Other technologies, which have notyet gained industrial application, may be considered, including thedirect catalytic oxidation of allyl chloride to epichlorohydrin usinghydrogen peroxide, or the chlorination of glycerol to dichloropropanol,followed by alkaline dehydrochlorination of the dichloropropanol thusformed to epichlorohydrin.

In accordance with the invention it has been found that a problem,particularly when chlorohydrins are employed that are obtained bychlorinating polyhydroxylated aliphatic hydrocarbons in adehydrochlorination reaction, is the presence of halogenated ketonesformed as by-products. These halogenated ketones may have boilingtemperatures close to those of the epoxides and may be difficult toseparate by a distilling operation. In accordance with the invention ithas also been found that the halogenated ketones, even at lowconcentration, are responsible for the development of an undesirablecoloration of the epoxide or of products produced from it. This is moreparticularly the case for chloroacetone, which is formed in the processof dehydrochlorinating dichloropropanol to form epichlorohydrin.

It has also been found that, surprisingly, these ketones can be removedduring the preparation of the epoxide.

The invention therefore provides a process for preparing an epoxide,wherein halogenated ketones are formed as by-products and whichcomprises at least one treatment to remove at least part of thehalogenated ketones formed.

The invention provides more specifically a process for preparing anepoxide, wherein halogenated ketones are formed as by-products and whichcomprises at least one treatment intended to remove at least part of thehalogenated ketones formed, and wherein the epoxide is prepared bydehydrochlorinating a chlorohydrin.

The chlorohydrin may be obtained by a process of hypochlorinating anolefin or by a process of chlorinating a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof.

The term “epoxide” is used here to describe a compound containing atleast one oxygen bridged on a carbon-carbon bond. In general the carbonatoms of the carbon-carbon bond are adjacent and the compound maycontain atoms other than carbon and oxygen atoms, such as hydrogen atomsand halogens. The preferred epoxides are ethylene oxide, propyleneoxide, glycidol and epichlorohydrin.

The term “olefin” is used here to describe a compound containing atleast one carbon-carbon double bond. In general the compound may containatoms other than carbon atoms, such as hydrogen atoms and halogens. Thepreferred olefins are ethylene, propylene, allyl chloride and mixturesof at least two thereof.

The term “polyhydroxylated aliphatic hydrocarbon” refers to ahydrocarbon which contains at least two hydroxyl groups attached to twodifferent saturated carbon atoms. The polyhydroxylated aliphatichydrocarbon may contain, but is not limited to, from 2 to 60 carbonatoms.

Each of the carbons of a polyhydroxylated aliphatic hydrocarbon carryingthe hydroxyl (OH) functional group may not possess more than one OHgroup and must be of sp3 hybridization. The carbon atom carrying the OHgroup may be primary, secondary or tertiary. The polyhydroxylatedaliphatic hydrocarbon used in the present invention must contain atleast two sp3-hybridized carbon atoms carrying an OH group. Thepolyhydroxylated aliphatic hydrocarbon includes any hydrocarboncontaining a vicinal diol (1,2-diol) or a vicinal triol (1,2,3-triol),including higher orders of these repeating units, which are vicinal orcontiguous. The definition of the polyhydroxylated aliphatic hydrocarbonalso includes, for example, one or more 1,3-, 1,4-, 1,5- and 1,6-diolfunctional groups. The polyhydroxylated aliphatic hydrocarbon may alsobe a polymer such as polyvinyl alcohol. Geminal diols, for example, areexcluded from this class of polyhydroxylated aliphatic hydrocarbons.

The polyhydroxylated aliphatic hydrocarbons may contain aromaticmoieties or heteroatoms including, for example, heteroatoms of halogen,sulphur, phosphorus, nitrogen, oxygen, silicon and boron type, andmixtures thereof.

Polyhydroxylated aliphatic hydrocarbons which can be used in the presentinvention include, for example, 1,2-ethanediol (ethylene glycol),1,2-propanediol (propylene glycol), 1,3-propanediol,1-chloro-2,3-propanediol (chloropropanediol), 2-chloro-1,3-propanediol(chloropropanediol), 1,4-butanediol, 1,5-pentanediol, cyclohexanediols,1,2-butanediol, 1,2-cyclohexanedimethanol, 1,2,3-propanetriol (alsoknown as glycerol or glycerin), and mixtures thereof. With preferencethe polyhydroxylated aliphatic hydrocarbon used in the present inventionincludes, for example, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol,chloropropanediol and 1,2,3-propanetriol, and mixtures of at least twothereof. More preferably the polyhydroxylated aliphatic hydrocarbon usedin the present invention includes, for example, 1,2-ethanediol,1,2-propanediol, chloropropanediol and 1,2,3-propanetriol and mixturesof at least two thereof. 1,2,3-Propanetriol, or glycerol, is the mostpreferred.

The esters of polyhydroxylated aliphatic hydrocarbon may be present inthe polyhydroxylated aliphatic hydrocarbon and/or may be produced in theprocess of preparing the chlorohydrin and/or may be prepared prior tothe process of preparing the chlorohydrin. Examples of esters ofpolyhydroxylated aliphatic hydrocarbon include ethylene glycolmonoacetate, propanediol monoacetates, glycerol monoacetates, glycerolmonostearates, glycerol diacetates and mixtures thereof.

In the process according to the invention, the esters of thepolyhydroxylated aliphatic hydrocarbon may originate from the reactionof the polyhydroxylated aliphatic hydrocarbon with an organic acid,before, during or within the steps which follow the reaction with thechlorinating agent.

The term “chlorohydrin” is used here to describe a compound containingat least one hydroxyl group and at least one chlorine atom which areattached to different saturated carbon atoms. A chlorohydrin whichcontains at least two hydroxyl groups is also a polyhydroxylatedaliphatic hydrocarbon. Hence the starting material and the product ofthe reaction may each be chlorohydrins. In that case the “product”chlorohydrin is more chlorinated than the starting chlorohydrin; inother words, it has more chlorine atoms and fewer hydroxyl groups thanthe starting chlorohydrin. Preferred chlorohydrins are chloroethanol,chloropropanol, chloropropanediol, dichloropropanol and mixtures of atleast two thereof. Dichloropropanol is particularly preferred.Chlorohydrins which are more particularly preferred are 2-chloroethanol,1-chloropropan-2-ol, 2-chloropropan-1-ol, 1-chloropropane-2,3-diol,2-chloropropane-1,3-diol, 1,3-dichloropropan-2-ol,2,3-dichloropropan-1-ol and mixtures of at least two thereof.

The chlorohydrin in the process according to the invention may beobtained starting from fossil raw materials or starting from renewableraw materials, preferably starting from renewable raw materials.

By fossil raw materials are meant materials obtained from the treatmentof petrochemical natural resources, for example petroleum, natural gasand coal. Among these materials the organic compounds containing 2 and 3carbon atoms are preferred. When the chlorohydrin is dichloropropanol orchloropropanediol, allyl chloride, allyl alcohol and “synthetic”glycerol are particularly preferred. By “synthetic” glycerol is meant aglycerol obtained generally starting from petrochemical resources. Whenthe chlorohydrin is chloroethanol, ethylene and “synthetic” ethyleneglycol are particularly preferred. By “synthetic” ethylene glycol ismeant an ethylene glycol obtained generally starting from petrochemicalresources. When the chlorohydrin is monochloropropanol, propylene and“synthetic” propylene glycol are particularly preferred. By “synthetic”propylene glycol is meant a propylene glycol obtained generally startingfrom petrochemical resources.

By renewable raw materials are meant materials obtained from thetreatment of renewable natural resources. Among these materials“natural” ethylene glycol, “natural” propylene glycol and “natural”glycerol are preferred. “Natural” ethylene glycol, propylene glycol andglycerol are obtained, for example, by conversion of sugars viathermochemical processes, it being possible for these sugars to beobtained starting from biomass, as described in “Industrial Bioproducts:Today and Tomorrow”, Energetics, Incorporated for the U.S. Department ofEnergy, Office of Energy Efficiency and Renewable Energy, Office of theBiomass Program, July 2003, pages 49, 52 to 56. One of these processesis, for example, the catalytic hydrogenolysis of sorbitol obtained bythermochemical conversion of glucose. Another process is, for example,the catalytic hydrogenolysis of xylitol obtained by hydrogenatingxylose. The xylose may be obtained, for example, by hydrolysing thehemicellulose present in maize fibres. By “natural glycerol” or by“glycerol obtained starting from renewable raw materials” is meant, inparticular, glycerol obtained during the production of biodiesel or elseglycerol obtained in the course of conversions of animal or vegetableoils or fats in general, such as saponification, transesterification orhydrolysis reactions.

Among the oils which can be used for preparing the natural glycerolmention may be made of all customary oils, such as palm oil, palm kerneloil, copra oil, babassu oil, former or new (low erucic acid) colza,sunflower oil, maize oil, castor oil and cotton oil, peanut oil,soyabean oil, linseed oil and crambe oil, and all oils obtained, forexample, from sunflower or colza plants obtained by genetic modificationor hybridization.

It is also possible to utilize used frying oils, various animal oils,such as fish oils, tallow, lard and even squaring greases.

Among the oils used it is also possible to indicate oils partiallymodified, for example, by polymerization or oligomerization, such as,for example, the stand oils of linseed oil and sunflower oil, and blownvegetable oils.

One particularly suitable glycerol may be obtained during the conversionof animal fats. Another particularly suitable glycerol may be obtainedduring the production of biodiesel. A third, very suitable glycerol maybe obtained during the conversion of animal or vegetable oils or fats bytransesterification in the presence of a heterogeneous catalyst, asdescribed in documents FR 2752242, FR 2869612 and FR 2869613. Morespecifically, the heterogeneous catalyst is selected from mixed oxidesof aluminium and zinc, mixed oxides of zinc and titanium, mixed oxidesof zinc, titanium and aluminium, and mixed oxides of bismuth andaluminium, and the heterogeneous catalyst is employed in the form of afixed bed. This latter process may be a biodiesel production process.

The chloroethanol may be obtained starting from these raw materials byany process. The processes of hypochlorinating ethylene and ofchlorinating “synthetic” and/or “natural” ethylene glycol are preferred.The process of chlorinating “synthetic” and/or “natural” ethylene glycolis particularly preferred.

The chloropropanol may be obtained starting from these raw materials byany process. The processes of hypochlorinating propylene andchlorinating “synthetic” and/or “natural” propylene glycol arepreferred. The process of chlorinating “synthetic” and/or “natural”propylene glycol is particularly preferred.

The chloropropanediol may be obtained starting from these raw materialsby any process. The process of chlorinating “synthetic” and/or “natural”glycerol is preferred.

The dichloropropanol may be obtained starting from these raw materialsby any process. The processes of hypochlorinating allyl chloride,chlorinating allyl alcohol and chlorinating “synthetic” and/or “natural”glycerol are preferred. The process of chlorinating “synthetic” and/or“natural” glycerol is particularly preferred.

In the process for preparing the epoxide according to the invention, itis preferable for at least a fraction of the chlorohydrin to be preparedby chlorinating a polyhydroxylated aliphatic hydrocarbon. Thepolyhydroxylated aliphatic hydrocarbon may be “synthetic” or “natural”in the senses defined above.

In the preparation process according to the invention, when the epoxideis epichlorohydrin, preference is given to “natural” glycerol, in otherwords glycerol obtained in the course of biodiesel production or in thecourse of conversions of animal or vegetable oils or fats, theconversions being selected from saponification, transesterification andhydrolysis reactions. Glycerol obtained by transesterification of fatsor oils of vegetable or animal origin, the transesterification beingcarried out in the presence of a heterogeneous catalyst, is particularlypreferred. In the process for preparing the epoxide according to theinvention, the polyhydroxylated aliphatic hydrocarbon may be asdescribed in the patent application “Process for preparing chlorohydrinby converting polyhydroxylated aliphatic hydrocarbons”, filed in thename of SOLVAY SA on the same day as the present application, and thecontent of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinwherein a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof whose totalmetal content, the metals being expressed in the form of elements, isgreater than or equal to 0.1 μg/kg and less than or equal to 1000 mg/kg,is reacted with a chlorinating agent.

A first advantage associated with this latter type of glycerol is thatit contains little or no metals. These metals may be detrimental tocertain steps in the preparation of dichloropropanol, such as, forexample, residue treatment steps. A second advantage associated withthis latter type of glycerol is that it contains little or no heavyorganic compounds, which can accumulate in the preparation ofdichloropropanol. The purge operations intended to remove these heavyorganic products may consequently be reduced.

In the process for preparing the epoxide according to the invention, thechlorohydrin obtained starting from the polyhydroxylated aliphatichydrocarbon by reaction with a chlorinating agent may be employed, forexample, in accordance with the process described in application WO2005/054167 of SOLVAY SA, the content of which is incorporated here byreference.

In the process for preparing the epoxide according to the invention, thepolyhydroxylated aliphatic hydrocarbon may be a crude product or apurified product as described in application WO 2005/054167 of SOLVAYSA, from page 2 line 8 to page 4 line 2.

The crude product may contain fatty acids, fatty acid esters such as, inparticular, monoglycerides and diglycerides, optionally in combinationwith water or a metal salt. Preference is given to using a purifiedglycerol, i.e. one containing at least 80% and not more than 99.9% byweight of glycerol, at least 0.1% and not more than 20% by weight ofwater, at least 1 mg/kg and not more than 0.1% by weight of aldehyde,and at least 10 mg/kg and not more than 10% by weight of methanol and/orethanol.

In the process for preparing the epoxide according to the invention, thepolyhydroxylated aliphatic hydrocarbon may be a polyhydroxylatedaliphatic hydrocarbon whose alkali metal and/or alkaline earth metalcontent is less than or equal to 5 g/kg, as described in the applicationentitled “Process for preparing a chlorohydrin by chlorinating apolyhydroxylated aliphatic hydrocarbon”, filed in the name of SOLVAY SAon the same day as the present application, and the content of which isincorporated here by reference.

In the process according to the invention, the alkali metal and/oralkaline earth metal content of the polyhydroxylated aliphatichydrocarbon, the ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof is less than or equal to 5 g/kg, often less than orequal to 1 g/kg, more particularly less than or equal to 0.01 g/kg and,in certain cases, less than or equal to 2 mg/kg. The alkali metal and/oralkaline earth metal content of the polyhydroxylated aliphatichydrocarbon is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the alkali metals aregenerally lithium, sodium, potassium and caesium, often sodium andpotassium, and frequently sodium.

In the process for preparing a chlorohydrin according to the invention,the lithium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Saidcontent is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the sodium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the potassium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the rubidium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the caesium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the alkaline earth elementsare generally magnesium, calcium, strontium and barium, often magnesiumand calcium, and frequently calcium.

In the process according to the invention, the magnesium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the calcium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the strontium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the barium content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is generally less than orequal to 1 g/kg, often less than or equal to 0.1 g/kg and moreparticularly less than or equal to 2 mg/kg. Said content is generallygreater than or equal to 0.1 μg/kg.

In the process according to the invention, the alkali metals and/oralkaline earth metals are generally present in the form of salts,frequently in the form of chlorides, sulphates and mixtures thereof.Sodium chloride is the most often encountered.

In the process for preparing the epoxide according to the invention, thechlorinating agent of the polyhydroxylated aliphatic hydrocarbon may behydrogen chloride and/or hydrochloric acid as described in applicationWO 2005/054167 of SOLVAY SA, from page 4 line 30 to page 6 line 2.

The hydrogen chloride may originate from a process for pyrolysingorganic chlorine compounds, such as, for example, a vinyl chloridepreparation, a process for preparing 4,4-methylenediphenyl diisocyanate(MDI) or toluene diisocyanate (TDI), metal pickling processes, or thereaction of an inorganic acid such as sulphuric or phosphoric acid witha metal chloride such as sodium chloride, potassium chloride or calciumchloride.

In one advantageous embodiment of the process for preparing the epoxideaccording to the invention, the chlorinating agent of thepolyhydroxylated aliphatic hydrocarbon is gaseous hydrogen chloride oran aqueous solution of hydrogen chloride or a combination of the two.

In the process for preparing the epoxide according to the invention, thechlorinating agent of the polyhydroxylated aliphatic hydrocarbon may beaqueous hydrochloric acid or hydrogen chloride, preferably anhydrous,obtained from a process for preparing allyl chloride and/orchloromethanes and/or of chlorinolysis and/or of high-temperatureoxidation of chlorine compounds, as described in the applicationentitled “Process for preparing a chlorohydrin by reacting apolyhydroxylated aliphatic hydrocarbon with a chlorinating agent”, filedin the name of SOLVAY SA on the same day as the present application, andthe content of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinfrom a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof and achlorinating agent, the latter agent containing at least one of thefollowing compounds: nitrogen, oxygen, hydrogen, chlorine, an organichydrocarbon compound, an organic halogen compound, an organic oxygencompound and a metal.

Particular mention is made of an organic hydrocarbon compound selectedfrom saturated or unsaturated aliphatic and aromatic hydrocarbons andmixtures thereof.

Particular mention is made of an unsaturated aliphatic hydrocarbonselected from acetylene, ethylene, propylene, butene, propadiene,methylacetylene and mixtures thereof, of a saturated aliphatichydrocarbon selected from methane, ethane, propane, butane and mixturesthereof, and of an aromatic hydrocarbon which is benzene.

Particular mention is made of an organic halogen compound which is anorganic chlorine compound selected from chloromethanes, chloroethanes,chloropropanes, chlorobutanes, vinyl chloride, vinylidene chloride,monochloropropenes, perchloroethylene, trichloroethylene,chlorobutadienes, chlorobenzenes and mixtures thereof.

Particular mention is made of an organic halogen compound which is anorganic fluorine compound selected from fluoromethanes, fluoroethanes,vinyl fluoride, vinylidene fluoride and mixtures thereof.

Particular mention is made of an organic oxygen compound selected fromalcohols, chloroalcohols, chloroethers and mixtures thereof.

Particular mention is made of a metal selected from alkali metals,alkaline earth metals, iron, nickel, copper, lead, arsenic, cobalt,titanium, cadmium, antimony, mercury, zinc, selenium, aluminium, bismuthand mixtures thereof.

Mention is made more particularly of a process wherein the chlorinatingagent is obtained at least partly from a process for preparing allylchloride and/or from a process for preparing chloromethanes and/or froma process of chlorinolysis and/or from a process of oxidizing chlorinecompounds at a temperature greater than or equal to 800° C.

In one advantageous embodiment of the process for preparing the epoxideaccording to the invention, the chlorinating agent of thepolyhydroxylated aliphatic hydrocarbon contains no gaseous hydrogenchloride.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon maybe carried out in a reactor as described in application WO 2005/054167of SOLVAY SA, at page 6 lines 3 to 23.

Mention is made particularly of plant made of or covered with materialswhich under the reaction conditions are resistant to chlorinatingagents, especially to hydrogen chloride. Mention is made moreparticularly of plant made of enamelled steel or of tantalum.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofmay be carried out in apparatus made of or covered with materials whichare resistant to chlorinating agents, as described in the applicationentitled “Process for preparing a chlorohydrin in corrosion-resistantapparatus”, filed in the name of SOLVAY SA on the same day as thepresent application, and the content of which is incorporated here byreference.

Particular mention is made of a process for preparing a chlorohydrinwhich comprises a step wherein a polyhydroxylated aliphatic hydrocarbon,an ester of polyhydroxylated aliphatic hydrocarbon or a mixture thereofis subjected to reaction with a chlorinating agent containing hydrogenchloride and at least one other step carried out in apparatus made of orcovered with materials resistant to the chlorinating agent under theconditions in which said step is performed. Mention is made moreparticularly of metallic materials such as enamelled steel, gold andtantalum and of non-metallic materials such as high-densitypolyethylene, polypropylene, poly(vinylidene fluoride),polytetrafluoroethylene, perfluoroalkoxyalkanes and poly(perfluoropropylvinyl ether), polysulphones and polysulphides, and graphite, includingimpregnated graphite.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofmay be carried out in a reaction mixture as described in the applicationentitled “Continuous process for preparing chlorohydrins”, filed in thename of SOLVAY SA on the same day as the present application, and thecontent of which is incorporated here by reference.

Particular mention is made of a continuous process for producingchlorohydrin wherein a polyhydroxylated aliphatic hydrocarbon, an esterof a polyhydroxylated aliphatic hydrocarbon or a mixture thereof isreacted with a chlorinating agent and an organic acid in a liquidreaction mixture whose steady-state composition comprisespolyhydroxylated aliphatic hydrocarbon and esters of polyhydroxylatedaliphatic hydrocarbon with a sum content, expressed in moles ofpolyhydroxylated aliphatic hydrocarbon, of more than 1.1 mol % and lessthan or equal to 30 mol %, the percentage being based on the organicpart of the liquid reaction mixture.

The organic part of the liquid reaction mixture consists of all of theorganic compounds in the liquid reaction mixture, in other words thecompounds whose molecule contains at least 1 carbon atom.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon maybe carried out in the presence of a catalyst as described in applicationWO 2005/054167 of SOLVAY SA, from page 6 line 28 to page 8 line 5.

Mention is made particularly of a catalyst based on a carboxylic acid oron a carboxylic acid derivative having an atmospheric boiling point ofgreater than or equal to 200° C., especially adipic acid and adipic acidderivatives.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon maybe carried out at a catalyst concentration, temperature and pressure andfor residence times as described in application WO 2005/054167 of SOLVAYSA, from page 8 line 6 to page 10 line 10.

Mention is made particularly of a temperature of at least 20° C. and notmore than 160° C., a pressure of at least 0.3 bar and not more than 100bar and a residence time of at least 1 h and not more than 50 h.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon maybe carried out in the presence of a solvent as described in applicationWO 2005/054167 of SOLVAY SA, at page 11 lines 12 to 36.

Mention is made particularly of an organic solvent such as chlorinatedorganic solvent, an alcohol, a ketone, an ester or an ether, anon-aqueous solvent which is miscible with the polyhydroxylatedaliphatic hydrocarbon, such as chloroethanol, chloropropanol,chloropropanediol, dichloropropanol, dioxane, phenol, cresol, andmixtures of chloropropanediol and dichloropropanol, or heavy reactionproducts such as at least partly chlorinated and/or esterified oligomersof the polyhydroxylated aliphatic hydrocarbon.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon maybe carried out in the presence of a liquid phase comprising heavycompounds other than the polyhydroxylated aliphatic hydrocarbon, asdescribed in the application entitled “Process for preparing achlorohydrin in a liquid phase”, filed in the name of SOLVAY SA on thesame day as the present application, and the content of which isincorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinwherein a polyhydroxylated aliphatic hydrocarbon, an ester ofpolyhydroxylated aliphatic hydrocarbon or a mixture thereof is subjectedto reaction with a chlorinating agent in the presence of a liquid phasecomprising heavy compounds other than the polyhydroxylated aliphatichydrocarbon, the boiling temperature of said compounds under a pressureof 1 bar absolute being at least 15° C. greater than the boilingtemperature of the chlorohydrin under a pressure of 1 bar absolute.

In the process for preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofmay be carried out in batch mode or in continuous mode. Continuous modeis particularly preferred.

In the process of preparing the epoxide according to the invention, thereaction of chlorinating the polyhydroxylated aliphatic hydrocarbon ispreferably carried out in a liquid reaction mixture. The liquid reactionmixture may be single-phase or multi-phase.

The liquid reaction mixture is composed of the entirety of the dissolvedor dispersed solid compounds, dissolved or dispersed liquid compoundsand dissolved or dispersed gaseous compounds at the reactiontemperature.

The reaction mixture comprises the reactants, the catalyst, the solvent,the impurities present in the reactants, in the solvent and in thecatalyst, the reaction intermediates, the reaction products and thereaction by-products.

By reactants are meant the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon and the chlorinatingagent.

The impurities present in the polyhydroxylated aliphatic hydrocarbon mayinclude carboxylic acids, salts of carboxylic acids, fatty acid esterswith the polyhydroxylated aliphatic hydrocarbon, fatty acid esters withthe alcohols used in the transesterification, and inorganic salts suchas alkali metal or alkaline earth metal sulphates and chlorides.

When the polyhydroxylated aliphatic hydrocarbon is glycerol, theimpurities of the glycerol may include carboxylic acids, salts ofcarboxylic acids, fatty acid esters such as mono-, di- andtriglycerides, fatty acid esters with the alcohols used in thetransesterification, and inorganic salts such as alkali metal oralkaline earth metal sulphates and chlorides.

The reaction intermediates may include monochlorohydrins of thepolyhydroxylated aliphatic hydrocarbon and their esters and/orpolyesters, the esters and/or polyesters of the polyhydroxylatedaliphatic hydrocarbon, and the esters of polychlorohydrins.

When the chlorohydrin is dichloropropanol, the reaction intermediatesmay include the monochlorohydrin of glycerol and its esters and/orpolyesters, the esters and/or polyesters of glycerol, and the esters ofdichloropropanol.

The ester of polyhydroxylated aliphatic hydrocarbon may therefore be, asappropriate, a reactant, an impurity of the polyhydroxylated aliphatichydrocarbon or a reaction intermediate.

By reaction products are meant the chlorohydrin and water. The water maybe the water formed in the chlorination reaction and/or may be the waterintroduced into the process, for example via the polyhydroxylatedaliphatic hydrocarbon and/or the chlorinating agent, as described inapplication WO 2005/054167 of SOLVAY SA, at page 2 lines 22 to 28, atpage 3 lines 20 to 25, at page 5 lines 7 to 31 and at page 12 lines 14to 19.

The by-products may include, for example, partly chlorinated and/oresterified oligomers of the polyhydroxylated aliphatic hydrocarbon.

When the polyhydroxylated aliphatic hydrocarbon is glycerol, theby-products may include, for example, the partly chlorinated and/oresterified oligomers of glycerol.

The reaction intermediates and the by-products may be formed in thevarious steps of the process, such as, for example, during the step ofpreparing the chlorohydrin and during the steps of separating off thechlorohydrin.

The liquid reaction mixture may thus comprise the polyhydroxylatedaliphatic hydrocarbon, the chlorinating agent, dissolved or dispersed inthe form of bubbles, the catalyst, the solvent, the impurities presentin the reactants, the solvent and the catalyst, such as dissolved orsolid salts, for example, the reaction intermediates, the reactionproducts and the reaction by-products.

In the process according to the invention, the chlorohydrin may beseparated from the other compounds of the reaction mixture in accordancewith methods as described in application WO 2005/054167 of SOLVAY SA,from page 12 line 1 to page 16 line 35 and at page 18 lines 6 to 13.Particular mention is made of separation by azeotropic distillation of awater/chlorohydrin/chlorinating agent mixture under conditions whichminimize the losses of chlorinating agent, followed by separation of thechlorohydrin by decantation. These other compounds are those mentionedabove, and include unconsumed reactants, the impurities present in thereactants, the catalyst and the solvent, the solvent, the catalyst, thereaction intermediates, the water and the reaction by-products.

In the process for preparing the epoxide according to the invention, theseparation of the chlorohydrin and the other compounds from the reactionmixture from chlorination of the polyhydroxylated aliphatic hydrocarbonmay be carried out according to methods as described in patentapplication EP 05104321.4, filed in the name of SOLVAY SA on 20 May2005, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrin byreacting a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof with achlorinating agent wherein the polyhydroxylated aliphatic hydrocarbon,an ester of a polyhydroxylated aliphatic hydrocarbon or a mixturethereof that is used contains at least one solid or dissolved metalsalt, the process including a separating operation intended to removepart of the metal salt. Mention is made more particularly of a processfor preparing a chlorohydrin by reacting a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon of amixture thereof with a chlorinating agent wherein the polyhydroxylatedaliphatic hydrocarbon, an ester of a polyhydroxylated aliphatichydrocarbon or a mixture thereof that is used contains at least onesodium and/or potassium chloride and/or sulphate and wherein theseparating operation intended to remove part of the metal salt is afiltering operation. Mention is also made particularly of a process forpreparing a chlorohydrin wherein (a) a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof is subjected to reaction with a chlorinating agent in areaction mixture, (b) a fraction of the reaction mixture containing atleast the water and the chlorohydrin is removed continuously orperiodically, (c) at least one part of the fraction obtained in step (b)is introduced into a distillation step, and (d) the reflux ratio of thedistillation step is controlled by supplying water to said distillationstep. Mention is made very particularly of a process for preparing achlorohydrin wherein (a) a polyhydroxylated aliphatic hydrocarbon, anester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereofis subjected to reaction with hydrogen chloride in a reaction mixture,(b) a fraction of the reaction mixture containing at least the water inthe chlorohydrin is removed continuously or periodically, (c) at leastpart of the fraction obtained in step (b) is introduced into adistillation step, wherein the ratio between the hydrogen chlorideconcentration and the water concentration in the fraction introducedinto the distillation step is smaller than the ratio of hydrogenchloride/water concentrations in the binary azeotropic hydrogenchloride/water composition at the distillation temperature and pressure.

In the process for preparing the epoxide according to the invention, thechlorohydrin and the other compounds can be separated from the reactionmixture from chlorination of the polyhydroxylated aliphatic hydrocarbon,ester of polyhydroxylated aliphatic hydrocarbon or mixtures thereof bymethods as described in the application entitled “Process for preparinga chlorohydrin”, filed in the name of SOLVAY SA on the same day as thepresent application, and the content of which is incorporated here byreference.

Particular mention is made of a process for preparing a chlorohydrincomprising the following steps: (a) a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof is reacted with a chlorinating agent and an organic acidso as to give a mixture containing the chlorohydrin and esters of achlorohydrin, (b) at least part of the mixture obtained in step (a) issubjected to one or more treatments in steps subsequent to step (a), and(c) polyhydroxylated aliphatic hydrocarbon is added to at least one ofthe steps subsequent to step (a), so as to react, at a temperaturegreater than or equal to 20° C., with the esters of the chlorohydrin, soas to form, at least partly, esters of the polyhydroxylated aliphatichydrocarbon.

Mention is made more particularly of a process wherein thepolyhydroxylated aliphatic hydrocarbon is glycerol and the chlorohydrinis dichloropropanol.

In the process for preparing the epoxide according to the invention, thechlorohydrin and the other compounds can be separated from the reactionmixture from chlorination of the polyhydroxylated aliphatic hydrocarbon,ester of polyhydroxylated aliphatic hydrocarbon or a mixture thereof bymethods as described in the application entitled “Process for preparinga chlorohydrin starting from a polyhydroxylated aliphatic hydrocarbon”,filed in the name of SOLVAY SA on the same day as the presentapplication, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing chlorohydrin byreacting a polyhydroxylated aliphatic hydrocarbon, an ester ofpolyhydroxylated hydrocarbon or a mixture thereof with a chlorinatingagent in a reactor which is supplied with one or more liquid streamscontaining less than 50% by weight of the polyhydroxylated aliphatichydrocarbon, the ester of polyhydroxylated hydrocarbon or the mixturethereof, relative to the weight of the entirety of the liquid streamsintroduced into the reactor. More particular mention is made of aprocess comprising the following steps: (a) a polyhydroxylated aliphatichydrocarbon, an ester of polyhydroxylated hydrocarbon or a mixturethereof is reacted with a chlorinating agent so as to give at least onemixture containing the chlorohydrin, water and the chlorinating agent,(b) at least a fraction of the mixture formed in step (a) is removed,and (c) the fraction removed in step (b) is subjected to a distillingand/or stripping operation wherein polyhydroxylated aliphatichydrocarbon is added in order to separate, from the fraction removed instep (b), a mixture containing water and the chlorohydrin, having areduced chlorinating agent content as compared with that of the fractionremoved in step (b).

In the process for preparing the epoxide according to the invention, thechlorohydrin and the other compounds of the reaction mixture fromchlorination of the polyhydroxylated aliphatic hydrocarbon may beseparated by methods as described in the application entitled “Processfor converting polyhydroxylated aliphatic hydrocarbons intochlorohydrins”, filed in the name of SOLVAY SA on the same day as thepresent application, and the content of which is incorporated here byreference.

Particular mention is made of a process for preparing a chlorohydrincomprising the following steps: (a) a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof is reacted with a chlorinating agent so as to give amixture containing the chlorohydrin, chlorohydrin esters and water, (b)at least a fraction of the mixture obtained in step (a) is subjected toa distilling and/or stripping treatment so as to give a batchconcentrated with water, with chlorohydrin and with chlorohydrin esters,and (c) at least a fraction of the batch obtained in step (b) issubjected to a separating operation in the presence of at least oneadditive so as to give a portion concentrated with chlorohydrin and withchlorohydrin esters and containing less than 40% by weight of water.

The separating operation is more particularly a decantation.

In the process for preparing the epoxide according to the invention, theseparation and the treatment of the other compounds of the reactionmixture from chlorination of the polyhydroxylated aliphatic hydrocarbonmay be carried out by methods as described in the application entitled“Process for preparing a chlorohydrin by chlorinating a polyhydroxylatedaliphatic hydrocarbon”, filed in the name of SOLVAY SA on the same dayas the present application. One preferred treatment consists insubjecting a fraction of the reaction by-products to a high-temperatureoxidation.

Particular mention is made of a process for preparing a chlorohydrincomprising the following steps: (a) a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof whose alkali metal and/or alkaline earth metal contentis less than or equal to 5 g/kg, an chlorinating agent and an organicacid are reacted so as to give a mixture containing at least thechlorohydrin and by-products, (b) at least part of the mixture obtainedin step (a) is subjected to one or more treatments in steps subsequentto step (a), and (c) at least one of the steps subsequent to step (a)consists in an oxidation at a temperature greater than or equal to 800°C.

More particular mention is made of a process wherein, in the subsequentstep, a part of the mixture obtained in step (a) is removed and thispart is subjected to oxidation at a temperature greater than or equal to800° C. in the course of its removal. Particular mention is also made ofa process wherein the treatment of step (b) is a separating operationselected from phase separation, filtration, centrifugation, extraction,washing, evaporation, stripping, distillation and adsorption operationsor combinations of at least two thereof.

In the process according to the invention, when the chorohydrin ischloropropanol, said chloropropanol is generally obtained in the form ofa mixture of compounds comprising the isomers of 1-chloropropan-2-ol andof 2-chloropropan-1-ol. This mixture generally contains more than 1% byweight of the two isomers, preferably more than 5% by weight and inparticular more than 50%. The mixture usually contains less than 99.9%by weight of the two isomers, preferably less than 95% by weight andvery particularly less than 90% by weight. The other constituents of themixture may be compounds originating from the processes for preparingthe chloropropanol, such as residual reactants, reaction by-products,solvents and, in particular, water.

The mass ratio between the isomers 1-chloropropan-2-ol and2-chloropropan-1-ol is usually greater than or equal to 0.01, preferablygreater than or equal to 0.4. This ratio is usually less than or equalto 99 and preferably less than or equal to 25.

In the process according to the invention, when the chorohydrin ischloroethanol, said chloroethanol is generally obtained in the form of amixture of compounds comprising the isomer 2-chloroethanol. This mixturegenerally contains more than 1% by weight of the isomer, preferably morethan 5% by weight and in particular more than 50%. The mixture usuallycontains less than 99.9% by weight of the isomer, preferably less than95% by weight and very particularly less than 90% by weight. The otherconstituents of the mixture may be compounds originating from theprocesses for preparing the chloroethanol, such as residual reactants,reaction by-products, solvents and, in particular, water.

In the process according to the invention, when the chlorohydrin isdichloropropanol, said dichloropropanol is generally obtained in theform of a mixture of compounds comprising the isomers of1,3-dichloropropan-2-ol and of 2,3-dichloropropan-1-ol. This mixturegenerally contains more than 1% by weight of the two isomers, preferablymore than 5% by weight and in particular more than 50%. The mixtureusually contains less than 99.9% by weight of the two isomers,preferably less than 95% by weight and very particularly less than 90%by weight. The other constituents of the mixture may be compoundsoriginating from the processes for preparing the dichloropropanol, suchas residual reactants, reaction by-products, solvents and, inparticular, water.

The mass ratio between the isomers 1,3-dichloropropan-2-ol and2,3-dichloropropan-1-ol is usually greater than or equal to 0.01,preferably greater than or equal to 0.4. This ratio is usually less thanor equal to 99 and preferably less than or equal to 25.

In the process according to the invention, when the chlorohydrin isdichloropropanol and is obtained in a process starting from allylchloride, the isomer mixture exhibits a1,3-dichloropropan-2-ol:2,3-dichloropropan-1-ol mass ratio which isoften from 0.3 to 0.6, typically approximately 0.5. When thedichloropropanol is obtained in a process starting from synthetic and/ornatural glycerol, the 1,3-dichloropropan-2-ol:2,3-dichloropropan-1-olmass ratio is commonly greater than or equal to 1.5, often greater thanor equal to 3.0, frequently greater than or equal to 7.0 and veryparticularly greater than or equal to 20.0. When the dichloropropanol isobtained starting from allyl alcohol, the1,3-dichloropropan-2-ol:2,3-dichloropropan-1-ol mass ratio is often ofthe order of 0.1.

By halogenated ketones are meant ketones containing 3 to 18 carbonatoms, preferably 3 to 12 carbon atoms and, with particular preference,3 to 6 carbon atoms, and in which one or more hydrogen atoms have beenreplaced by a halogen atom. They are often chlorinated ketones, and moreparticularly chloroacetone.

These halogenated ketones may be produced under certain conditionsduring and/or prior to the dehydrochlorination of the chlorohydrin inthe processes for preparing the chlorohydrin. In the first case, whenthe chlorohydrin is dichloropropanol, and without wishing to be tied byany one theory, it is thought that the chloroacetone is essentiallygenerated starting from the isomer 1,3-dichloropropan-2-ol. In thesecond case, it has been found, surprisingly, that the halogenatedketones may be present in a large amount in the chlorohydrin obtained bya process of hydrochlorinating a polyhydroxylated aliphatic hydrocarbon.In this case the halogenated ketone content of the chlorohydrin obtainedis commonly greater than or equal to 0.005% by weight, relative to themixture of the isomers of the chlorohydrin, and often greater than orequal to 0.01% by weight. Said content is commonly less than or equal to0.4% by weight, relative to the mixture of isomers of the chlorohydrin,and preferably less than or equal to 0.3% by weight.

According to a first variant of the process according to the invention,the treatment intended to remove at least part of the halogenatedketones is carried out during the dehydrochlorination of thechlorohydrin.

By dehydrochlorination is meant the removal of hydrochloric acid,irrespective of the mechanism of this removal and the ultimate form inwhich the hydrochloric acid removed is obtained.

The dehydrochlorination may be carried out by any known means, forexample by heating the chlorohydrin in the absence of any reactant otherthan the chlorohydrin, by treating the chlorohydrin with a basiccompound, in the presence or absence of a catalyst. It is preferred tocarry out the dehydrochlorination by treating the chlorohydrin with abasic compound.

By basic compound is meant basic organic compounds or basic inorganiccompounds. Basic inorganic compounds are preferred. These basicinorganic compounds may be oxides, hydroxides and salts of metals, suchas carbonates, hydrogen carbonates, phosphates or mixtures thereof, forexample. Among the metals, preference is given to alkali metals andalkaline earth metals. Sodium, potassium and calcium and mixturesthereof are particularly preferred. The basic inorganic compounds may bepresent in the form of solids, liquids or aqueous or organic solutionsor suspensions. Aqueous solutions or suspensions are preferred. Thesolutions and suspensions of NaOH, of Ca(OH)₂, purified alkaline brineand mixtures thereof are particularly preferred. By purified alkalinebrine is meant the caustic soda, containing NaCl, of the kind producedin a diaphragm electrolysis process. The amount of basic compound in thesolution or suspension is generally greater than or equal to 1% byweight, preferably greater than or equal to 4% by weight and with veryparticular preference greater than or equal to 6% by weight. This amountis commonly less than or equal to 60% by weight. An amount ofapproximately 50% by weight is particularly appropriate.

The basic compound may be used in superstoichiometric, substoichiometricor stoichiometric amounts with respect to the chlorohydrin. When thebasic compound is used in substoichiometric amounts it is usual to usenot more than 2 moles of chlorohydrin per mole of base. It is common touse not more than 1.5 moles of chlorohydrin per mole of base andpreferably not more than 1.05 moles of chlorohydrin per mole of base.When the basic agent is used in superstoichiometric amounts use is madeof not more than 2 moles of base per mole of chlorohydrin. In this caseit is customary to use at least 1.05 moles of base per mole ofchlorohydrin.

The water content of the mixture comprising the chlorohydrin and thebasic compound is generally greater than or equal to 8% by weight.

When the dehydrochlorination is carried out by treating the chlorohydrinwith a basic compound, the reaction mixture may also contain a solventsuch as those described in U.S. Pat. No. 3,061,615 in the name of SOLVAYSA.

The dehydrochlorination may be carried out as described in theapplication entitled “Process for preparing an epoxide starting from apolyhydroxylated aliphatic hydrocarbon and a chlorinating agent”, filedin the name of SOLVAY SA on the same day as the present application, andthe content of which is incorporated here by reference.

Particular mention is made of a process for preparing an epoxide whereina reaction mixture resulting from the reaction of a polyhydroxylatedaliphatic hydrocarbon, an ester of a polyhydroxylated aliphatichydrocarbon or a mixture thereof with a chlorinating agent, the reactionmixture containing at least 10 g of chlorohydrin per kg of reactionmixture, is subjected to a subsequent chemical reaction withouttreatment in between.

Mention is also made of the preparation of an epoxide comprising thefollowing steps: (a) a polyhydroxylated aliphatic hydrocarbon, an esterof a polyhydroxylated aliphatic hydrocarbon or a mixture thereof isreacted with a chlorinating agent and an organic acid so as to form thechlorohydrin and chlorohydrin esters in a reaction mixture containingthe polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon, water, the chlorinating agentand the organic acid, the reaction mixture containing at least 10 g ofchlorohydrin per kg of reaction mixture, (b) at least a fraction of thereaction mixture obtained in step (a), said fraction having the samecomposition as the reaction mixture obtained in step (a), is subjectedto one or more treatments in steps subsequent to step (a), and (c) abasic compound is added to at least one of the steps subsequent to step(a) so as to react at least partly with the chlorohydrin, thechlorohydrin esters, the chlorinating agent and the organic acid so asto form the epoxide and salts.

The liquid reaction mixture may be single-phase or biphase.

The basic dehydrochlorination treatment may be executed in continuous ordiscontinuous mode.

The duration of the basic treatment or, where appropriate, the residencetime of the reactants during the basic treatment is generally greaterthan or equal to 0.1 s, preferably greater than or equal to 0.3 s andwith particular preference greater than or equal to 0.4 s. This durationor this residence time is commonly less than or equal to 2 h, moreespecially less than or equal to 1 h. The residence time of thereactants is defined as the ratio between the volume of the reactoroccupied by the liquid phase or phases and the cumulative flow rate ofthe reactants.

The basic dehydrochlorination treatment according to the invention isgenerally carried out at a temperature of at least 0° C. Often thistemperature is at least 20° C. Preferably it is at least 30° C. In theprocess for preparing the epoxide according to the invention, thereaction is generally carried out at a temperature of not more than 140°C. Preferably it is not more than 120° C. In a first particular variantthe temperature is from 25 to 50° C. In a second particular variant thetemperature is from 50 to 90° C.

In the process for preparing the epoxide according to the invention, thedehydrochlorination is generally carried out at a pressure of at least0.08 bar absolute. Often this pressure is at least 0.1 bar absolute.Preferably it is at least 0.2 bar absolute. In the process for preparingthe epoxide according to the invention, the dehydrochlorination isgenerally carried out at a pressure of not more than 25 bar absolute.Preferably it is not more than 6 bar absolute. In a first particularvariant the pressure is from 0.4 to 0.8 bar absolute. In a secondparticular variant the pressure is from 1 to 3 bar.

The epoxide which is formed in the process for dehydrochlorinating thechlorohydrin may be removed at the rate at which it is formed, by meansof distillation or stripping. Stripping may be carried out using any gaswhich is inert towards the epoxide. Preference is given to carrying outthis stripping with steam.

Following basic treatment, the halogenated ketone content of the epoxideis commonly less than or equal to 0.01% by weight, preferably less thanor equal to 0.005% by weight and with very particular preference lessthan or equal to 0.003% by weight. Often the epoxide contains at least0.0001% by weight of halogenated ketones.

The invention therefore likewise provides an epoxide whose halogenatedketone content is less than or equal to 0.01% by weight. When theepoxide is epichlorohydrin its purity is preferably greater than orequal to 999 g/kg.

Without wishing to be tied by any one theory, it is thought that thereactivities of the chlorohydrin, the halogenated ketones and theepoxide are such that it is possible to remove the halogenated ketoneswithout adversely affecting the yield of epoxide by judiciouslyselecting the conditions for dehydrochlorinating the chlorohydrin.

According to a second variant of the process according to the invention,the treatment intended to remove at least part of the halogenatedketones comprises a distillation, evaporation and/or stripping in thepresence of water, this treatment being carried out prior to thedehydrochlorination and enabling the removal of a fraction composedessentially of water and halogenated ketones and the recovery of thechlorohydrin having a reduced halogenated ketone content.

Following this treatment, the halogenated ketone content of thechlorohydrin is commonly less than or equal to 0.1% by weight relativeto the mixture of isomers of the chlorohydrin, preferably less than orequal to 0.04% by weight and with very particular preference less thanor equal to 0.005% by weight. Often the chlorohydrin contains at least0.0001% by weight of halogenated ketones relative to the mixture ofisomers of the chlorohydrin.

This treatment is preferably an azeotropic distillation in the presenceof water. The reason for this is that it has been found that, when thehalogenated ketone is chloroacetone, for example, the water and thechloroacetone form a low-point binary azeotropic mixture, whosecomposition can be characterized by its boiling temperature, which is92° C. at 1013 mbar. This composition is constituted, at thistemperature and pressure, by 28% by weight of water and 72% by weight ofchloroacetone. Two liquid phases separate after condensation at 25° C.;the denser, organic phase contains 95% by weight of chloroacetone and 5%by weight of water, while the aqueous phase contains 5% by weight ofchloroacetone and 95% by weight of water. It has been found that theexploitation of the properties of liquid/vapour equilibria of the binarywater/chloroacetone composition make it possible to remove thechloroacetone from dichloropropanol. The water required for theazeotropic distillation may originate, for example, from a process forsynthesizing the dichloropropanol, in particular by chlorination ofglycerol, or may be conveyed into the process subsequently.

The invention hence also provides an azeotropic composition comprisingwater and chloroacetone.

FIG. 1 shows a first particular scheme of plant which can be used toconduct the process for preparing an epoxide according to the invention.

A distillation column (3) is supplied via line (1) with thechlorohydrin. Water is added to the chlorohydrin via line (2). A streamwhich contains water and the majority of the halogenated ketones iswithdrawn continuously from column (3) via line (4). The residue of thecolumn, containing the purified chlorohydrin, is withdrawn via line (5).A basic compound is added to the residue of column (3) via line (6) andthe mixture obtained supplies a reactor, which can optionally serve as adistillation column (8), via line (7). Steam is introduced into thebottom of the reactor (8) via line (9). A gas stream is withdrawncontinuously from reactor (8) via line (10) and supplies a condenser(12). A liquid stream is withdrawn continuously from reactor (8) vialine (11). The condensed stream (13) supplies a phase separator (14).The aqueous phase separated off is returned to the top of reactor (8) bythe pipeline (15) in order to ensure reflux. The crude epoxide productconstitutes the organic phase separated off, which is withdrawn by thepipeline (16). This crude epoxide is purified in a distillation sector.

In a first particular aspect of the process according to the invention,chlorohydrin is employed which contains at least a part of thechlorohydrin obtained from a preparation, starting from apolyhydroxylated aliphatic hydrocarbon, by reaction with a chlorinatingagent. In this aspect the part of the chlorohydrin obtained from apreparation starting from the polyhydroxylated aliphatic hydrocarbon byreaction with a chlorinating agent makes up in general at least 1% byweight relative to the total weight of the chlorohydrin, preferably atleast 5% by weight and more particularly at least 35% by weight. In thisparticular aspect this fraction is generally not more than 99% by weightand preferably not more than 60% by weight. The extra chlorohydrin,which can be obtained from any one of the other processes for preparingthe chlorohydrin that have been envisaged above, is generally at least1% by weight, preferably at least 5% by weight and more particularly atleast 35% by weight. This fraction is not more than 99% by weight andpreferably not more than 60% by weight. Among these other processes forpreparing the chlorohydrin, preference is given to the hypochlorinationof an olefin.

The invention accordingly further provides a first process for preparingan epoxide, comprising:

-   (a) a step of preparing a chlorohydrin by hypochlorinating an    olefin,-   (b) a step of preparing the chlorohydrin by chlorinating a    polyhydroxylated aliphatic hydrocarbon, which is carried out in    parallel with step (a), and-   (c) a common dehydrochlorination step in which the chlorohydrin    obtained in steps (a) and (b) is employed.

Preferably this first process for preparing the epoxide comprises a stepof treatment intended to remove at least part of the halogenated ketonesformed in the process.

According to a first embodiment of the first process for preparing theepoxide according to the invention, a mixture of the chlorohydrinobtained in steps (a) and (b) is employed in step (c).

FIG. 2 shows a second particular scheme of plant which can be used toconduct the process for preparing an epoxide according to thisembodiment.

A distillation column (20) is supplied via line (18) with thechlorohydrin originating from a reactor for chlorinating apolyhydroxylated aliphatic hydrocarbon (17). Water is added to thechlorohydrin via line (19). A stream which contains water andhalogenated ketones is withdrawn continuously from column (20) via line(21). The residue of the column is withdrawn via line (22) and is mixedwith a stream of the chlorohydrin (24) obtained from a reactor forhypochlorinating an olefin (23). A basic compound is added to the mixedstream of the chlorohydrin via line (25), and the mixture obtainedsupplies a reactor, which can optionally serve as distillation column(27), via line (26). Steam is introduced into the bottom of the reactor(27) via line (28). A gas stream is withdrawn continuously from reactor(27) via line (29) and supplies a condenser (31). A liquid stream iswithdrawn continuously from reactor (27) via line (30). The condensedstream (32) supplies a phase separator (33). The aqueous phase separatedoff is returned to the top of reactor (27) by the pipeline (34), inorder to ensure reflux. The crude oxide product constitutes the organicphase separated off, which is withdrawn by the pipeline (35). This crudeepoxide is purified in a distillation sector.

According to a second embodiment of the first process for preparing theepoxide according to the invention, the chlorohydrin obtained in step(a) or in step (b) is employed alternatively or simultaneously in step(c).

The invention likewise provides plant for preparing an epoxide,comprising:

-   (a) a reactor for hypochlorinating an olefin, from which exits a    reaction mixture containing a chlorohydrin,-   (b) a reactor for chlorinating a polyhydroxylated aliphatic    hydrocarbon, from which exits a reaction mixture containing the    chlorohydrin, and-   (c) a reactor for dehydrochlorinating which is supplied with the    reaction mixtures produced from reactor (a) and from reactor (b).

This plant for preparing an epoxide preferably comprises a reactor forthe treatment of removing at least part of the halogenated ketonesformed in the plant.

The conditions of step (b) may be those described in application WO2005/054167 of SOLVAY SA and in application EP 05104321.4, filed in thename of SOLVAY SA on May 20, 2005. The conditions of step (c) are, forexample, as described earlier on above in the present application.

FIG. 3 shows a third particular scheme of plant which can be used toconduct the process for preparing an epoxide according to the invention.

A stream of chlorohydrin (37) coming from a reactor for chlorinating apolyhydroxylated aliphatic hydrocarbon (36) is mixed with a stream ofthe chlorohydrin (39) obtained from a reactor for hypochlorinating anolefin (38). A basic compound is added to the mixed stream of thechlorohydrin via line (40), and the mixture obtained supplies a reactor,which can optionally serve as distillation column (42), via line (41).Steam is introduced into the bottom of the reactor (42) via line (43). Agas stream is withdrawn continuously from reactor (42) via line (44) andsupplies a condenser (46). A liquid stream is withdrawn continuouslyfrom reactor (42) via line (45). The condensed stream (47) supplies aphase separator (48). The aqueous phase separated off is returned to thetop of reactor (42) by the pipeline (49), in order to ensure reflux. Thecrude oxide product constitutes the organic phase separated off, whichis withdrawn by the pipeline (50). This crude epoxide is purified in adistillation sector.

In a second particular aspect of the process according to the invention,epoxide is obtained at least part of which has come from the separatepreparation of the epoxide starting from a chlorohydrin obtained byreacting a polyhydroxylated aliphatic hydrocarbon with a chlorinatingagent. In this aspect, the part of the chlorohydrin obtained from thepreparation starting from the chlorinated aliphatic hydrocarbon byreaction with a chlorinating agent makes up generally at least 1% byweight relative to the total weight of the epoxide, preferably at least5% by weight and more particularly at least 35% by weight. In thisparticular aspect this fraction is generally not more than 99% by weightand preferably not more than 60% by weight. The extra epoxide may havecome from any one of the other processes for preparing the chlorohydrinthat were envisaged above and is generally at least 1% by weight,preferably at least 5% by weight and more particularly at least 35% byweight. This fraction is not more than 99% by weight and preferably notmore than 60% by weight.

Among these other processes for preparing the chlorohydrin, preferenceis given to hypochlorinating an olefin.

The invention hence additionally provides a second process for preparingan epoxide, comprising:

-   (a) a step of preparing a chlorohydrin by hypochlorinating an    olefin,-   (b) a step of dehydrochlorinating the chlorohydrin obtained in    step (a) to give the epoxide in a dehydrochlorination reaction    mixture,-   (c) a step of preparing the chlorohydrin by chlorinating a    polyhydroxylated aliphatic hydrocarbon,-   (d) a step of dehydrochlorinating the chlorohydrin obtained in    step (c) to give the epoxide in a dehydrochlorination reaction    mixture, and-   (e) a step of separating the epoxide from the dehydrochlorination    reaction mixtures, in which the dehydrochlorination reaction mixture    containing the epoxide, obtained in steps (b) and (d), is employed,    and wherein step (b) is consecutive to step (a), step (d) is    consecutive to step (c), and the pairing consisting of steps (a)    and (b) is parallel to the pairing consisting of steps (c) and (d).

Preferably this second process for preparing an epoxide comprises a stepof treatment intended to remove at least part of the halogenated ketonesformed in the process.

According to a first embodiment of the second process for preparing theepoxide according to the invention, a mixture of the epoxide obtained insteps (b) and (d) is employed in step (e).

According to a second embodiment of the second process for preparing theepoxide according to the invention, the epoxide obtained in step (b) orin step (d) is employed alternatively or simultaneously in step (e).

The invention likewise provides plant for preparing an epoxide,comprising:

-   (a) a reactor for hypochlorinating an olefin, from which exits a    reaction mixture containing a chlorohydrin,-   (b) a reactor for dehydrochlorinating which is supplied with the    reaction mixture produced from reactor (a), and from which exits a    reaction mixture containing the epoxide,-   (c) a reactor for chlorinating a polyhydroxylated aliphatic    hydrocarbon, from which exits a reaction mixture containing the    chlorohydrin,-   (d) a reactor for dehydrochlorinating, which is supplied with the    reaction mixture produced from reactor (b), and which produces a    reaction mixture containing the epoxide, and-   (e) a separator which is supplied with the reaction mixtures exiting    from reactor (b) and from reactor (d),    and in which reactor (b) is consecutive to reactor (a), reactor (d)    is consecutive to reactor (c), and the pairing consisting of    reactors (a) and (b) is parallel with the pairing consisting of    reactors (c) and (d).

This plant for preparing an epoxide preferably comprises a reactor forthe treatment of removing at least part of the halogenated ketonesformed in the plant.

The conditions of step (c) may be those described in application WO2005/054167 in the name of SOLVAY SA and in application EP 05104321.4,filed in the name of SOLVAY SA on 20 May 2005. The conditions of steps(c) and (d) are, for example, those described earlier on above in thepresent application.

The process for preparing the epoxide according to the invention may beintegrated into an overall scheme as described in the applicationentitled “Process for preparing an epoxide starting from achlorohydrin”, filed in the name of SOLVAY SA on the same day as thepresent application, and the content of which is incorporated here byreference.

Particular mention is made of a process for preparing an epoxidecomprising at least a step of purification of the epoxide formed, theepoxide being at least partly prepared by a process fordehydrochlorinating a chlorohydrin, said chlorohydrin being at leastpartly prepared by a process of chlorinating a polyhydroxylatedaliphatic hydrocarbon, an ester of a polyhydroxylated aliphatichydrocarbon or a mixture thereof.

It has been proved that it is possible to enhance the capacity of plantsfor preparing epoxides from fossil raw materials in an economic waywithout increasing consumption of these raw materials.

FIG. 4 shows a fourth particular scheme of plant which can be used toconduct the process for preparing an epoxide according to the invention.

A distillation column (54) is supplied with chlorohydrin originatingfrom a reactor for chlorinating a polyhydroxylated aliphatic hydrocarbon(51) via line (52). Water is added to the chlorohydrin via line (53). Astream containing water and halogenated ketones is withdrawncontinuously from column (54) via line (55). The residue of the column(54) is withdrawn via line (56). A basic compound is added to theresidue of the column (54) via line (57), and the mixture obtainedsupplies a reactor, which can optionally serve as distillation column(59), via line (58). Steam is introduced into the bottom of reactor (59)via line (60). A gas stream is withdrawn continuously from reactor (59)via line (61) and supplies a condenser (63). A liquid stream iswithdrawn continuously from reactor (59) via line (62). The condensedstream (64) supplies a phase separator (65). The aqueous phase separatedoff is returned to the top of reactor (59) by the pipeline (66) in orderto ensure reflux. The crude epoxide product constitutes the organicphase separated off, which is withdrawn by pipeline (67).

Another reactor which can optionally serve as distillation column (71)is supplied with chlorohydrin originating from a reactor forhypochlorinating an olefin (68) via line (69), and a basic compound isadded to the chlorohydrin via line (70). Steam is introduced into thebottom of reactor (71) via line (72). A gas stream is withdrawncontinuously from reactor (71) via line (73) and supplies a condenser(75). A liquid stream is withdrawn continuously from reactor (71) vialine (74). The condensed stream (76) supplies a phase separator (77).The aqueous phase separated off is returned to the top of reactor (71)by pipeline (78) in order to ensure reflux. The crude epoxide productconstitutes the organic phase separated off, which is withdrawn bypipeline (79). The two streams of the crude epoxide are collectedbeforehand with a view to purification in a common distillation sectorvia line (80).

The processes and plant described above are preferred when the epoxideis ethylene oxide, the chlorohydrin is chloroethanol, thepolyhydroxylated aliphatic hydrocarbon is ethanediol and the olefin isethylene.

The processes and plant described above are more preferred when theepoxide is propylene oxide, the chlorohydrin is chloropropanol, thepolyhydroxylated aliphatic hydrocarbon is propanediol and the olefin ispropylene.

The processes and plant described above are particularly preferred whenthe epoxide is glycidol, the chlorohydrin is chloropropanediol, thepolyhydroxylated aliphatic hydrocarbon is glycerol and the olefin isallyl chloride.

The processes and plant described above are very particularly preferredwhen the epoxide is epichlorohydrin, the chlorohydrin isdichloropropanol, the polyhydroxylated aliphatic hydrocarbon is glyceroland the olefin is allyl chloride.

When the epoxide is epichlorohydrin the processes and plant forpreparing the epoxide may be followed by processes and plant forproducing epoxy resins.

The examples below illustrate the invention, but without limiting it.

EXAMPLE 1

84 g of concentrated aqueous sodium hydroxide solution at 50% by weight(1.05 mol) are added to a solution of 129 g of 1,3-dichloropropan-2-olin 950 ml of water. The dichloropropanol contains 3 g/kg ofchloroacetone. After 1 minute of reaction at ambient temperature theconversion of the 1,3-dichloropropan-2-ol is complete, the selectivityfor epichlorohydrin is 99.9% and the relative chloroacetone contentrelative to the epichlorohydrin produced is reduced to 11 mg/kg. Theselectivity for products of hydrolysis of epichlorohydrin is 0.1%.

EXAMPLE 2

A mixture of 434.6 g of 1,3-dichloropropan-2-ol containing 3.7 g/kg ofchloroacetone was distilled following addition of 66.5 g of water.

The distillation was carried out under atmospheric pressure by means ofan adiabatic plate column surmounted by a device allowing a part of thevapour phase to flow back at the top of the column. The reflux ratio atthe top of the column was set at 57%.

The results table below describes the composition of the variousfractions collected:

Tempera- 1,3 ture at Dichloro- head of Chloro- propan- column Massacetone 2-ol Water Fraction ° C. g g/kg g/kg g/kg Starting mixture 488.73.2 864.2 132.6 Distilled fraction 1 94 1.77 56 181 762 Distilledfraction 2 99 3.54 32 231 737 Distilled fraction 3 99 3.33 25 241 734Distilled fraction 4 98 7.87 23 283 695 Distilled fraction 5 95 11.62 26261 713 Distilled fraction 6 97 12.3 25 227 749 Residue in boiler 433.801 927 72

40.43 g of distillate were harvested in 6 fractions, and each distillatefraction was biphase. The concentrations given in the table relate tothe sum of the two phases. This distillation made it possible to remove60% of the chloroacetone initially present, with a total loss limited to1.8% of 1,3-dichloropropan-2-ol in the distillates.

1. A process for preparing epichlorohydrin, comprising chlorinatingglycerol, an ester thereof, or a mixture thereof to producedichloropropanol, and dehydrochlorinating at least a fraction of thedichloropropanol to produce epichlorohydrin, wherein chloroacetoneformed as a by-product in said process is at least partially removedduring, prior to, or both during and prior to the dehydrochlorinating,said removal during said dehydrochlorinating comprising treating thedichloropropanol with a substoichiometric amount of a basic compound ata temperature of 25 to 50° C., said removal prior to saiddehydrochlorinating comprising at least one treatment selected from thegroup consisting of distillation, evaporation and stripping in thepresence of water, said treatment removing a fraction comprising waterand chloroacetone and providing dichloropropanol having a reducedcontent of chloroacetone.
 2. The process according to claim 1,comprising chlorinating glycerol, wherein the glycerol is obtainedstarting from renewable raw materials.
 3. The process according to claim1, wherein the chloroacetone is at least partially removed during thedehydrochlorinating, and wherein the basic compound is selected fromaqueous suspensions or solutions of NaOH, of Ca(OH)₂, purified alkalinebrine and mixtures thereof, and wherein the dehydrochlorinating iscarried out in batch mode or in continuous mode for a reactant residencetime or duration greater than or equal to 0.1 s and less than or equalto 2 h and at a pressure of at least 0.8 bar absolute and not more than25 bar absolute.
 4. The process according to claim 1, wherein saidchloroacetone is at least partially removed prior to thedehydrochlorinating, and wherein the chloroacetone content of thedichloropropanol following the treatment is less than or equal to 0.1%by weight and greater than or equal to 0.0001% by weight.
 5. The processaccording to claim 1, further comprising preparing dichloropropanol by(a) hypochlorinating allyl chloride in parallel with (b) said preparingdichloropropanol by chlorinating glycerol, an ester thereof, or amixture thereof, and dehydrochlorinating dichloropropanol obtained from(a) and (b) in (c) a common dehydrochlorination of dichloropropanol toproduce epichlorohydrin, wherein said chloroacetone is at leastpartially removed during, prior to, or both during and prior to thecommon dehydrochlorination.
 6. The process according to claim 5, whereina mixture of dichloropropanol obtained in (a) and (b) is employed in(c), or wherein dichloropropanol obtained in (a) or in (b) is employedalternatively or simultaneously in (c).
 7. The process according toclaim 2, wherein the glycerol is obtained during the production ofbiodiesel or during conversions of animal or vegetable oils and fats,the conversions being selected from saponification, transesterificationand hydrolysis reactions.
 8. The process according to claim 7, whereinthe glycerol is obtained by a transesterification reaction is performedin the presence of a heterogeneous catalyst.
 9. Epichlorohydrin having achloroacetone content of at least 0.0001% by weight and less than orequal to 0.01% by weight.
 10. The epichlorohydrin according to claim 9whose purity is greater than or equal to 999 g/kg.
 11. Theepichlorohydrin according to claim 9, having a chloroacetone content ofat least 0.0001% by weight and less than or equal to 0.005% by weight.12. The epichlorohydrin according to claim 9, having a chloroacetonecontent of at least 0.0001% by weight and less than or equal to 0.003%by weight.
 13. The process according to claim 1, further comprisingforming an epoxy resin from said epichlorohydrin.
 14. The processaccording to claim 1, wherein said chloroacetone is at least partiallyremoved during, and not prior to, the dehydrochlorinating.
 15. Theprocess according to claim 1, wherein said chloroacetone is at leastpartially removed prior to, and not during, the dehydrochlorinating. 16.The process according to claim 1, wherein said chloroacetone is at leastpartially removed both during and prior to the dehydrochlorinating. 17.A process comprising forming an epoxy resin from the epichlorohydrinaccording to claim
 9. 18. A process comprising forming an epoxy resinfrom the epichlorohydrin according to claim
 11. 19. A process comprisingforming an epoxy resin from the epichlorohydrin according to claim 12.20. The process according to claim 1, wherein the chloroacetone is atleast partially removed during the dehydrochlorinating, and wherein thebasic compound is selected from aqueous suspensions or solutions ofNaOH, of Ca(OH)₂, purified alkaline brine and mixtures thereof, whereinthe amount of basic compound in the solution or suspension is greaterthan or equal to 1% by weight and less than or equal to 60% by weight.21. The process according to claim 20, wherein the amount of basiccompound in the solution or suspension is approximately 50% by weight.22. The process according to claim 1, further comprising: (a) preparingdichloropropanol by hypochlorinating allyl chloride, (b)dehydrochlorinating the dichloropropanol obtained in (a) to giveepichlorohydrin in a dehydrochlorination reaction mixture, (c) preparingdichloropropanol by chlorinating glycerol, an ester thereof, or amixture thereof, (d) dehydrochlorinating the dichloropropanol obtainedin (c) to give epichlorohydrin in a dehydrochlorination reactionmixture, and (e) separating epichlorohydrin from the dehydrochlorinationreaction mixtures, in which a dehydrochlorination reaction mixturecomprising epichlorohydrin, obtained in (b) and (d), is employed, andwherein (b) is consecutive to (a), (d) is consecutive to (c), and thepairing of (a) and (b) is parallel to the pairing of (c) and (d).